Ion implanters of different designs are currently commercially available from a number of sources including Axcelis Technologies, Inc., assignee of the present invention. Two commercially available implanters are sold under the model designations MC3 and 8250. These tools create an ion beam that operates on batches of workpieces or on individual workpieces, one at a time. One typical application of an ion implanter is used to dope a semiconductor wafer with an ion impurity to produce a semiconductor material in the region treated by the ion beam. Although not limited to such wafers the invention has particular utility in such a doping process and the term workpiece and wafer are used interchangeably henceforth in this application.
Single wafer ion implanters currently available for semiconductor device manufacturing are designed for implanting an entire surface of the wafer. It is desirable to be able to implant different regions of the wafer with different implant species or dose or energy to enable a multiple split, split lot device experiment to be conducted on a single wafer. Conducting multiple implants on different regions of the same wafer offers the opportunity to reduce process development costs and also improves control of the experiment since all process steps are carried out on the same wafer.
U.S. Pat. No. 6,750,462 to Iwasawa et al concerns an ion implanting method that both scans an ion beam in an X direction and mechanically drives a substrate in a Y direction. An implanting step is featured for implanting ions separately for two implanted regions with different dose amounts of the substrate is executed plural times by changing at the center of the substrate a driving speed of the substrate.